1. Technical Field
The present invention relates to a liquid ejecting head unit that ejects liquid from a nozzle and a liquid ejecting apparatus, and particularly relates to an ink jet recording head unit that discharges ink as liquid and an ink jet recording apparatus.
2. Related Art
Representative examples of a liquid ejecting head unit that ejects liquid include an ink jet recording head unit that discharges drops of ink. For example, JPA-2009-6730 proposes an ink jet recording head unit that includes an ink jet recording head, which discharges drops of ink from a nozzle, and a passage member, which is fixed to the ink jet recording head and supplies ink from a liquid reservoir in which the ink is stored, such as an ink cartridge, to a liquid ejecting head.
The passage member of the ink jet recording head unit includes an upstream passage member, to which the ink is supplied from the liquid reservoir, and a downstream passage member, which holds the ink jet recording head and supplies the ink from the upstream passage member to the ink jet recording head. The passage member performs hermetic sealing so as to prevent the ink from leaking from a connection passage by causing a sealing member made of a plate-like elastic material, such as a sheet, to be pinched between the upstream passage member and the downstream passage member.
However, when it is attempted to hermetically seal the passage in which the upstream passage member and the downstream passage member are connected using the sealing member pinched between two members and made of an elastic material, such as a rubber sheet, repulsion based on elastic deformation of the sealing member may cause pressure to be applied in a direction in which the upstream passage member and the downstream passage member are separated from each other, and pressure may be applied in a direction perpendicular to a liquid ejecting surface that discharges the drops of ink of the liquid ejecting head. As a result, a malfunction may occur, such as separation of the passage member and the liquid ejecting head, separation of a layer member that is a constituent of the liquid ejecting head, or deviation from positions at which the drops of ink are expected to be supplied on an ejected medium, which is caused by warping of the liquid ejecting surface of the liquid ejecting head.
In contrast, JP-A-2003-305873 proposes a structure in which two passages are connected through a tube. Although the connection of two passages through a tube may reduce pressure in a direction perpendicular to a liquid ejecting surface, it is necessary to fit the tube to both an upper passage and a lower passage and assembling may be complicated.
Besides, in both cases in which the plate-like sealing member is used and the tube-like sealing member is used, it is necessary to press the upstream passage member relatively against the downstream passage member in assembling the upstream passage member and the downstream passage member, and the pressing may cause pressure to be applied in the direction in which the upstream passage member and the downstream passage member are separated from each other.
Similar to the ink jet recording head unit, the liquid ejecting head unit that ejects liquid other than ink also has such possibilities.
An advantage of some aspects of the invention is to propose a liquid ejecting head unit and a liquid ejecting apparatus, which enable passages to be connected preferably and improve assembility.